Respiratory assistance apparatus

ABSTRACT

A respiratory assistance apparatus ( 4 ) is provided, adapted to deliver gases to a user or patient ( 1 ). The apparatus ( 4 ) comprises a housing ( 10 ) provided with a chamber ( 5 ) and a heater ( 25 ), the chamber ( 5 ) comprising at least one gas port ( 15 ) connected to, or arranged to be connected to, at least one intermediate passageway ( 12 ). The apparatus ( 4 ) is operative according to a disinfection mode of predetermined profile in which the heater ( 25 ) heats liquid in the chamber ( 5 ) to produce vapour at or above a target dewpoint temperature and/or humidity level. The apparatus ( 4 ) is arranged such that the vapour is delivered to the intermediate passageway ( 12 ) to disinfect the intermediate passageway ( 12 ) with moist heat throughout a predetermined duration of the disinfection mode. Associated attachments and methods are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.61/758,663, filed on 30 Jan. 2013, the contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a respiratory assistance apparatus adapted todeliver respiratory gases to a user or patient. More particularly, theinvention relates to a respiratory assistance apparatus provided with adisinfection mode and a method of disinfecting a respiratory assistanceapparatus using a disinfection mode.

2. Description of the Related Art

A respiratory assistance apparatus typically comprises a humidifier, agases inlet to supply a gases flow from a gases source to thehumidifier, and a patient outlet to deliver a gases flow from thehumidifier to the user or patient. The gases source can be a blower,fan, pressurised tank, compressor, or the like. An inspiratory tube canbe connected between the patient outlet and a patient interface that isarranged to be mounted at or on the face of the user or patient. Thepatient interface may comprise a full face mask, nasal mask, nasalcannula, oral mouthpiece, or tracheostomy fitting.

One form of respiratory assistance apparatus can comprise an integratedsystem, where the gases source and the humidifier are contained withinthe same housing. With an integrated system, the patient outlet istypically mounted on the housing, and the humidifier and the patientoutlet are typically connected via an intermediate passageway located atleast partially within the housing.

Such respiratory assistance apparatus may be used in hospitals, otherhealthcare organisations, and care homes for example. They may also beused at the home of a user or patient. It is a problem in any suchenvironment to keep a respiratory assistance apparatus clean and freefrom potentially harmful bacteria. It is often desirable that at leastsome components of the apparatus can be reused with subsequent users orpatients, rather than requiring a new apparatus for each user orpatient. In such circumstances, it is important that the apparatus canbe cleaned to a sufficiently high standard for safe reuse. Inparticular, it may be required that some components of the apparatus canbe disinfected, even if other components, such as the inspiratory tubeand the patient interface, are to be replaced.

It is not usually required to disinfect components that are in the gasesflow path up to the chamber inlet, because the gases that contact suchcomponents are typically relatively dry external air or oxygen. However,it is often necessary to clean the components in the subsequent gasesflow path that are subjected to moisture, because moisture issusceptible to carrying bacteria which can cause the establishment andgrowth of biofilms that can be transmitted to the patient. Whilst somecomponents are accessible and therefore can be relatively easily cleaned(e.g., some patient interfaces may be placed in a dishwasher), othercomponents are contained within the housing, or may have internalfeatures that are difficult to access, and thus are not easily cleaned.One example of such a component is the aforementioned intermediatepassageway that links the humidifier to the patient outlet. In somecases, components cannot easily be removed from the apparatus forcleaning, or at least not without specialist or relatively skilledpersonnel. Removal of components also introduces a risk of damage to thecomponents or the apparatus, or of incorrect refitting of the componentsafter cleaning.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a respiratoryassistance apparatus, and a method of disinfecting a respiratoryassistance apparatus, which overcomes or at least ameliorates one ormore of the disadvantages of the prior art, or alternatively at leastprovides the public or industry with a useful choice.

Further objects of the invention will become apparent from the followingdescription.

Accordingly, in one aspect the invention may broadly be said to consistin a respiratory assistance apparatus adapted to deliver a gases flow toa user or patient, comprising a housing provided with a chamber and aheater, the chamber comprising at least one chamber port connected to,or arranged to be connected to, at least one intermediate passageway,the apparatus being operative according to a disinfection mode ofpredetermined profile in which the heater heats a liquid in the chamberto produce vapour or steam at or above a setpoint temperature, namely atarget dewpoint temperature, the apparatus being arranged such that thevapour is delivered to the intermediate passageway to disinfect theintermediate passageway with moist heat, the vapour at or above thetarget dewpoint temperature continuing to be delivered to theintermediate passageway throughout the predetermined duration of thedisinfection mode.

The predetermined profile may include a combination of some or all ofduration, temperature, moisture and pressure.

The at least one chamber port may comprise a chamber inlet port and achamber outlet port, the chamber inlet port being arranged to be influid communication in use with a gases source in the housing. The gasessource may comprise a blower, fan or compressor arranged to deliver agases flow through the chamber inlet port and into the chamber. Sucharrangements are not essential due to the expansion of the heated waterbut are preferred to prevent steam being delivered to other componentsof the apparatus via the chamber inlet port. Such components may besusceptible to damage if subjected to steam or chemical vapours fromdisinfection. Alternatively, a valve could be used to prevent anundesirable flow of vapour, directing such flow of vapour through thechamber outlet port.

In one example, the chamber comprises part of a humidifier of theapparatus, the humidifier being arranged to humidify the gases flowprior to delivery of the gases flow to the user or patient when theapparatus is operating in a non-disinfection mode. In this example, theliquid used during the disinfection mode may be a liquid normally usedfor humidification purposes. One example of a suitable humidificationliquid is water.

In another example, the chamber comprises a disinfection chamber. Inthis example, the liquid used during the disinfection mode may be adisinfecting and/or sterilising liquid. One example of a suitabledisinfecting and/or sterilising liquid is a mixture of water and adisinfecting and/or sterilising chemical. The disinfection chamber maybe provided with a liquid injection port to enable disinfecting and/orsterilising liquid to be injected into the chamber. Alternatively, thedisinfection chamber may be sealed, having been pre-charged withdisinfecting and/or sterilising liquid prior to use in the disinfectionmode.

The chamber may be removably mounted on the apparatus. The chamber maybe reusable or disposable.

The chamber may comprise an identifier, the apparatus being operative todetect the identifier and thus the presence of the chamber. Theidentifier may comprise a chamber inlet port arranged to have a highflow resistance which can be detected by the apparatus to identify thepresence of the chamber. The high flow resistance also prevents vapourundesirably passing through the chamber inlet port into the housing, bycausing local high flow velocity at the chamber inlet port when a gasesflow is delivered through the chamber inlet port from the housing.

The intermediate passageway may comprise an internal passageway locatedat least partially within the housing. The intermediate passageway maycomprise a conduit or elbow.

The intermediate passageway preferably directly or indirectly connects agases inlet that allows a gases flow into the housing with a patientoutlet that delivers a gases flow to the user or patient.

One end of the intermediate passageway may comprise the patient outlet.

In one example, during the disinfection mode, the end of theintermediate passageway comprising the patient outlet is connected tothe chamber outlet port via a removable disinfection tube which deliversvapour or steam to the intermediate passageway. The disinfection tubemay be heated. In this example, the at least one port of the chamber isconnected to the at least one intermediate passageway, by way of atemporary connection, that is, a connection used specifically forcleaning or disinfection.

In another example, the chamber outlet port is directly connected to theintermediate passageway at an opposed end from the patient outlet. Inthis example, the at least one port of the chamber is connected to theat least one intermediate passageway by way of a permanent connection,that is, a connection that remains after termination of the disinfectionmode.

The intermediate passageway may comprise an elbow having opposed endslinked by an intermediate bent portion. In one example, the bent portionis bent through 90°.

The intermediate passageway may be provided with at least one sensoroperative to generate a signal indicative of, for example, flow rate,moisture content or temperature at or proximate to the intermediatepassageway.

A cap may be provided comprising an engaging formation arranged toengage with one end of the intermediate passageway to mount the cap onsaid end, the cap comprising a flow restrictor arranged to restrict flowof fluid through the intermediate passageway when the cap is so mounted,to provide back pressure in the intermediate passageway during thedisinfection mode. Additionally or alternatively, the cap may comprisean antibacterial filter. The cap may comprise an identifier.Non-limiting examples of a suitable identifier include a magnet, an RFIDtag, or a source of electrical resistance such as a resistor.

The apparatus may be operative to heat the liquid to produce vapour ator above a target dewpoint temperature, that is, a fixed dewpointtemperature determined prior to initiation of the disinfection mode.Preferably, the target dewpoint temperature is a minimum dewpointtemperature required for effective disinfection by moist heat.

The apparatus may be operative to heat the liquid to produce vapour ator above a dewpoint temperature selected by a clinician or user, thatis, a variable dewpoint temperature determined before or afterinitiation of the disinfection mode.

The target dewpoint temperature may be greater than 70° C., ispreferably greater than 80° C., and is most preferably greater than 90°C. The presence of moist heat in the gases flow enables the targetdewpoint temperature to be substantially reduced as compared to targettemperatures of prior methods using dry or non-humidified air.

Note, in this and other aspects of the invention, that the targetdewpoint temperature may be set and measured within the chamber (e.g.,at the chamber outlet port) and/or within the intermediate passagewayand/or subsequent thereto. The target dewpoint temperature may requireadjustment depending on where it is measured to ensure adequatedisinfection efficacy.

Further, the target dewpoint temperature may be defined by a dewpointtemperature range.

Yet further, the target dewpoint temperature may be varied within thedisinfection cycle. For example, in one example disinfection cycle, thetarget dewpoint temperature may generally be relatively low, say around70° C., and increased for a short portion of the cycle to say 90° C.,potentially reducing the time required for disinfection and/or betterensuring adequate disinfection efficacy.

The apparatus may be operative to control the duration of thedisinfection mode in dependence upon the target and/or a measureddewpoint temperature. The apparatus may be operative to control theduration of the disinfection mode by reference to a lookup table, analgorithm or a formula relating the duration of the disinfection mode toa range of target and/or measured dewpoint temperatures.

In addition to reducing the temperature required for disinfection, theuse of vapour in the gases flow can also reduce the length of timerequired for disinfection. For example, 15 to 45 minutes may suffice,preferably around 30 minutes.

Preferably, the apparatus comprises a chamber sensor operative togenerate a signal indicative of whether the chamber is mounted on theapparatus. The chamber sensor may be operative to generate a signalindicative of whether a specific chamber is mounted on the apparatus.The chamber sensor may comprise the combination of a pressure/flowsensor and a flow restriction on the specific chamber, the flowrestriction restricting gases flow through the chamber which can bedetected by the pressure/flow sensor.

Preferably, the apparatus comprises a patient interface sensor operativeto generate a signal indicative of whether a patient interface isconnected to the apparatus, and to activate the disinfection mode onlywhen the signal indicates that a patient interface is not connected tothe apparatus. The patient interface sensor may be operative to detectthe presence of a cap or other attachment used in disinfection on oneend of the intermediate passageway, and to generate the signalindicative that a patient interface is connected to the apparatus, whenno cap or other disinfection mode attachment is detected.

Preferably, the apparatus comprises a disinfection mode sensor operativeto generate a disinfection mode activation signal. The disinfection modesensor may be operative to generate the disinfection mode activationsignal by detecting at least one of: a cap or other disinfection modeattachment being mounted on one end of the intermediate passageway; thechamber being mounted on the housing; and/or a clinician or user input.

The apparatus may comprise a chamber liquid level detector operative togenerate a signal indicative of the liquid level in the chamber. Theapparatus may be operative, in dependence upon the liquid level signaldetected, to vary at least one of: the flow rate of the gases flowexiting the chamber; the target dewpoint temperature of the vapour;and/or the duration of the disinfection mode.

A liquid level detector may additionally or alternatively be used todetect whether the chamber includes a sufficient level of liquid tocomplete a disinfection process. This may be a predetermined, fixedlevel or an adaptable level based on the parameters of the process beingused. An alarm or indicator light or display may alert a user to aninsufficient level of liquid. Disinfection mode may be inhibited untilsufficient liquid is present in the chamber, or a notification may begenerated indicating that disinfection has not completed.

Preferably, the required level of liquid is determined prior toinitiation of disinfection to optimize the disinfection mode. Note,however, that rather than having to repeat disinfection in the event ofa shortage of liquid, the target dewpoint temperature and/or theduration of the disinfection process may simply be increased, with thesebeing closer to parameters used in prior art arrangements that do notinclude the use of moist heat.

Additionally or alternatively, the chamber may be provided with avisible mark whereby a user fills the chamber to or above that markprior to disinfection.

Additionally or alternatively, a chamber that is specifically used fordisinfection may be pre-charged or filled with a predetermined amount ofliquid that has been determined to be sufficient to provide the requireddisinfection efficacy.

Depending on the liquid used, there may be an additional purging orrinsing step after disinfecting to remove or neutralise said liquid.

The apparatus may include a drying mode that is initiated subsequent tothe disinfection mode, wherein the intermediate passageway and/or othercomponents are dried. This may be achieved using heat generated by theheater when all of the liquid has been completely used, or via aseparate heater element, or by increasing the gases flow rate throughthe intermediate passageway, for example. The duration of the dryingmode may be predetermined, clinician or user controlled, or controlledin dependence on moisture levels detected in the intermediatepassageway.

According to a second aspect, the invention may broadly be said toconsist in a cap for use with a respiratory assistance apparatusaccording to the first aspect of the invention, the cap comprising anengaging formation arranged to engage with one end of the intermediatepassageway of the respiratory assistance apparatus to mount the cap onsaid end, the cap comprising a flow restrictor arranged to restrict flowthrough the intermediate passageway when the cap is so mounted toprovide back pressure in the intermediate passageway during thedisinfection mode.

The flow restrictor may comprise a filter. The filter may be ananti-bacterial filter. The filter may be arranged to prevent leakage ofliquid through or around the filter. The geometry of the cap may bearranged to prevent liquid contacting the filter.

The flow restrictor may comprise an orifice.

The cap may comprise a temperature sensor operative to generate a signalindicative of the temperature of the gases flow at or proximate to thecap.

The cap may comprise an identifier. Non-limiting examples of a suitableidentifier include a magnet, an RFID tag, or a source of electricalresistance such as a resistor. The identifier may simply identify thetype of device (i.e., the cap as opposed to other items that may beconnected thereto). This may be used by the apparatus to switch to adisinfection mode on detection of the cap and/or to generate an errormessage to a user that the apparatus is not correctly configured if adisinfection mode is otherwise selected and the cap is not detected.

The cap may comprise an open-ended cavity which defines a volumesuitable for measuring an amount of a liquid for use in the apparatus.

According to a third aspect, the invention may broadly be said toconsist in a method of disinfecting a respiratory assistance apparatusadapted to deliver a gases flow to a user or patient, according to adisinfecting mode, the apparatus comprising a chamber provided with aport in fluid communication with an intermediate passageway, the methodcomprising the steps of: heating a liquid in the chamber to producevapour or steam at or above a target dewpoint temperature; deliveringthe vapour through the port to the intermediate passageway; andcontinuing to deliver vapour at or above the target dewpoint temperaturethrough the port to the intermediate passageway throughout apredetermined duration of the disinfection mode.

The target dewpoint temperature may be predetermined, that is, fixedprior to initiation of the disinfection mode.

The method may include a step, prior to the heating step, of setting orselecting the target dewpoint temperature before or after initiation ofthe disinfection mode.

The target dewpoint temperature may be greater than 70° C., ispreferably greater than 80° C., and is most preferably greater than 90°C.

The method may include an additional step of controlling the duration ofthe disinfection mode in dependence upon the target and/or a measureddewpoint temperature. The method may include an additional step ofreferencing a lookup table using an algorithm or a formula relating theduration of the disinfection mode to a range of target and/or measureddewpoint temperatures.

The method may include an additional step of drying the intermediatepassageway, after delivering the vapour for the predetermined duration.

As with previous and further aspects, the liquid may be water, adisinfecting and/or sterilising chemical, and/or a mixture thereof.Where a chemical or chemicals are used, an additional step of purging orrising the apparatus may be performed whereby water or a neutralisingchemical is flushed therethrough.

According to a fourth aspect, the invention may broadly be said toconsist in a respiratory assistance apparatus adapted to deliver a gasesflow to a user or patient, comprising a housing provided with a chamberand a heater, the chamber comprising at least one port connected to, orarranged to be connected to, at least one intermediate passageway, theapparatus being operative according to a disinfection mode ofpredetermined profile in which the heater heats liquid in the chamber toproduce vapour or steam at or above a target dewpoint temperature, theapparatus being arranged such that the vapour is delivered to theintermediate passageway to disinfect the intermediate passageway withmoist heat, the apparatus further comprising a cap arranged to bemounted at one end of the intermediate passageway, the cap beingprovided with a flow restriction arranged to provide a back pressure inthe intermediate passageway during the disinfection mode.

The heater may subsequently be used, once all liquid in the chamber hasbeen completely used, to heat the gases flow within the apparatus to drythe intermediate passageway.

According to a fifth aspect, the invention may broadly be said toconsist in a respiratory assistance apparatus adapted to deliver a gasesflow to a user or patient, comprising a housing having a patient outlet,a chamber, and an intermediate gases flow path between the patientoutlet and the chamber, the apparatus being operative during adisinfection mode of predetermined profile, to generate and delivervapour or steam at or above a target dewpoint temperature from thechamber to the intermediate gases flow path to disinfect theintermediate gases flow path with moist heat throughout thepredetermined duration of the disinfection mode.

According to a sixth aspect, the invention may broadly be said toconsist in a method of disinfecting a respiratory assistance apparatusadapted to deliver a gases flow to a user or patient according to adisinfecting mode comprising the steps of: connecting a chamber to theapparatus; heating liquid in the chamber to produce vapour or steam ator above a target dewpoint temperature; and delivering the vapour to acomponent of the apparatus to disinfect that component with moist heat.

According to a seventh aspect, the invention may broadly be said toconsist in a respiratory assistance apparatus adapted to deliver a gasesflow to a patient, comprising a housing having a gases inlet and apatient outlet, the gases inlet being in communication with the patientoutlet via an intermediate passageway, the apparatus further comprisinga humidifier arranged between the gases inlet and the patient outlet andcomprising a chamber and heater arranged, in a respiratory assistancemode, to humidify the gases flow prior to delivery of the gases flow tothe patient outlet, the apparatus also being arranged, according to adisinfection mode of predetermined profile, to control the heater toheat the liquid in the chamber to produce vapour or steam at or above atarget dewpoint temperature, and to deliver the vapour to theintermediate passageway to disinfect the intermediate passageway withmoist heat throughout the predetermined duration of the disinfectionmode.

According to an eighth aspect, the invention may broadly be said toconsist in a respiratory assistance apparatus adapted to deliver a gasesflow to a user or patient, comprising a housing provided with a gasesinlet, the gases inlet being in fluid communication with a patientoutlet to deliver a gases flow to the patient via an intermediatepassageway, and a chamber and a heater, a controller being providedoperative to control the apparatus according to a disinfection mode inwhich the heater heats liquid to produce vapour or steam at or above atarget dewpoint temperature, the apparatus being arranged such that thevapour is delivered to the intermediate passageway to disinfect theintermediate passageway with moist heat, the disinfection mode having apredetermined duration, the controller being operative to subsequentlycontrol the apparatus such that the vapour at or above the targetdewpoint temperature continues to be delivered to the intermediatepassageway throughout the predetermined duration of the disinfectionmode.

The apparatus may comprise a safety cap provided with a connectorarranged to fluidly couple the safety cap to a downstream end of theintermediate passageway, and a duct forming a vapour flow path into thesafety cap, the safety cap being adapted to disperse and/or condensevapour received thereby. The safety cap may comprise a condensingsurface onto which vapour from the duct condenses and/or a condensatereservoir adapted to receive condensate generated by the safety cap.

According to another aspect, there is provided a respiratory assistanceapparatus adapted to deliver a gases flow to a user or patient, theapparatus comprising a housing provided with or configured to receive achamber and a heater, the chamber comprising at least one port connectedto, or arranged to be connected to, at least one intermediatepassageway, the apparatus being operative according to a disinfectionmode to heat liquid in the chamber to generate vapour or steam at orabove a target dewpoint temperature and deliver the vapour from thechamber to the intermediate passageway to disinfect the intermediatepassageway with moist heat, the apparatus further comprising a safetycap provided with a connector arranged to connect and/or fluidly couplethe safety cap to a downstream end of the intermediate passageway,thereby defining a gases pathway from the chamber to the safety cap, thesafety cap being adapted to, in use in the disinfection mode, disperseand/or condense at least a portion of vapour received thereby.

The may comprise a duct defining the gases pathway into the safety cap,the safety cap further comprising a condensing surface onto which vapourfrom the duct condenses. Additionally or alternatively, the apparatusmay comprise a condensate collector adapted to collect at least aportion of the condensate generated by the safety cap.

According to another aspect, there is provided a safety cap for use withthe respiratory apparatus of any one of the previous aspects, the safetycap comprising a connector arranged to fluidly couple the safety cap toa downstream end of the intermediate passageway, and a duct forming avapour flow path into the safety cap, the safety cap being adapted to,in use in a disinfecting mode, disperse and/or condense vapour receivedthereby.

Preferably, the safety cap comprises a condensing surface onto whichvapour from the duct condenses. The condensing surface may have asurface area greater than the cross sectional area of the duct and/or adomed ceiling into which the duct directs the vapour flow path. A skirtmay extend generally downwards from a peripheral edge of the ceiling todefine an area for holding vapour and/or directing flow of condensate.

The safety cap may be adapted to direct vapour radially outwardly of theconnector prior to the vapour impacting on the condensing surface,aiding in dispersion of the vapour and reducing the likelihood oflocalized hot spots. The duct may be defined by a wall having at leastone vapour outlet through which vapour can flow away from a longitudinalaxis of the duct. The or each vapour outlet comprises a slit formed inthe wall defining the duct. The condensing surface may be connected tothe duct via at least one spoke extending between the condensing surfaceand the duct. A vapour outlet may be provided in the wall of the ductbetween one or more adjacent pairs of said spokes. The duct may beterminated at an end distal from the intermediate passageway by an endwall.

The safety cap may comprise an identifier. The identifier may comprise aresistor, the resistance of which is detected by the apparatus when thesafety cap is mounted on the apparatus.

The safety cap may comprise one or more surfaces having a hydroscopicstructure arranged to promote the formation of condensate. Additionallyor alternatively, microstructures may be arranged to channel flow ofcondensate. The safety cap may comprise a condensate collector thatdefines a reservoir into which condensed vapour is collected. Thecondensate collector may comprise a substantially annular catch trayextending around the periphery of the connector. The condensatecollector may comprise a spout to facilitate pouring of liquid from thecondensate reservoir. Further, the condensate reservoir may be arrangedto measure a pre-determined volume of liquid for use during thedisinfecting mode of the respiratory apparatus.

According to another aspect, there is provided a respiratory assistanceapparatus adapted to deliver gas to a user or patient, the apparatuscomprising a housing provided with or configured to receive a chamberand a heater, the chamber comprising at least one gas port connected to,or arranged to be connected to, at least one intermediate passageway,the apparatus being operative according to a vapour disinfection mode todisinfect the at least one intermediate passageway with moist heat, theapparatus comprising a controller for controlling operation of theapparatus in the disinfection mode, to activate the heater to heatliquid in the chamber to generate vapour at or above a target dewpointtemperature for at least a portion of the duration of the disinfectionmode.

In an initialization phase, the controller may be arranged to detect thepresence or absence of any one or more of the chamber, an attachment foruse with the apparatus in the disinfection mode, and liquid in thechamber, and/or a level of liquid in the chamber.

The apparatus may comprise a compressor in fluid communication with thechamber for urging gases through the chamber to the at least oneintermediate passageway, wherein during a warm up phase and/or a maindisinfecting phase, the controller is adapted to control the heater togenerate vapour and to control the compressor to provide no or only alow level of increased flow.

Prior to termination of the disinfection mode, the controller may beconfigured to control the compressor to provide a ramped increase inflow so as to dry and/or cool down the at least one intermediatepassageway. The controller may be configured to switch off the heaterand/or the compressor upon detection of any one or more of an absence ofliquid in the chamber, a temperature of a portion of the apparatusfalling below a predetermined threshold, a temperature detected insidethe apparatus falling below a predetermined threshold and elapse of apredetermined time period.

Preferably, the compressor is controlled to slowly discharge anyremaining vapour or steam from the chamber near the end of thedisinfection mode and then to provide a higher flow rate subsequentthereto so as to provide for accelerated drying and/or cooling. Theinitial low flow helps to prevent injury since relatively high energysteam or vapour is ejected relatively slowly before the lower energy airstream is forced from the chamber at a higher flow.

The controller may be arranged to generate a signal indicative ofwhether the disinfection mode was completed successfully and/or log oneor more parameters relating to the disinfection mode.

Further aspects of the invention, which should be considered in all itsnovel aspects, will become apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

A number of embodiments of the invention will now be described by way ofexample with reference to the drawings.

FIG. 1 is a perspective view of a respiratory assistance apparatus inaccordance with the invention, in use with an inspiratory tube andpatient interface.

FIG. 2 is a partially exploded perspective view of a respiratoryassistance apparatus in accordance with the invention.

FIG. 3 is a perspective view of a further respiratory assistanceapparatus in accordance with the present invention, with the device in apartially disassembled condition.

FIG. 4 is a perspective view of the apparatus of FIG. 3 in an assembledcondition.

FIG. 5 is a perspective view of the apparatus of FIGS. 1 and 2,including a cap closing a patient outlet.

FIG. 6 is a perspective sectional view of a cap for use with anapparatus in accordance with the invention.

FIG. 7 is a further perspective view of an apparatus in accordance withthe present invention.

FIG. 8 is a perspective view of a respiratory assistance apparatus inaccordance with the invention, including a safety cap.

FIG. 9 is a sectional view of the safety cap of FIG. 8.

FIG. 10 is a perspective sectional view of the cap of FIG. 9, with acondensate reservoir of the safety cap removed.

FIG. 11 is a perspective sectional view of the safety cap of FIGS. 9 and10, with a condensate reservoir of the safety cap removed and analternative top part.

FIG. 12 is a perspective sectional view of a lower part of the safetycap of FIGS. 9 and 10, with an upper part of the safety cap removed.

FIG. 13 is a perspective view of the lower part of the safety cap ofFIG. 12, with an upper part of the safety cap removed.

FIG. 14 is a perspective view of the safety cap of FIGS. 9 and 10.

FIG. 15 is a perspective view of the safety cap having the alternativetop part of FIG. 11.

FIG. 16 is an overview of a steam disinfection control system of arespiratory assistance apparatus and method in accordance with theinvention.

FIG. 17 is a schematic of the steam disinfection control system of FIG.16.

FIG. 18 is a flow diagram showing steps used in the steam disinfectioncontrol system of FIGS. 16 and 17.

FIG. 19 is a flow diagram of a temperature control system forming partof the steam disinfection control system of FIGS. 16 to 18.

FIG. 20 is a flow diagram of a gases flow control system forming part ofthe steam disinfection control system of FIGS. 16 to 19.

FIG. 21 is a schematic view of a resistance detection circuitry used inconnection with the safety cap of FIGS. 8 to 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Throughout the description like reference numerals will be used to referto like features in different embodiments.

The present invention provides a respiratory assistance apparatus thatprovides a convenient, effective and reliable method of disinfecting atleast a portion of the apparatus with moist heat during a disinfectionmode, which portion may define, at least in part, a transport path for ahumidified gases flow generated by the apparatus. According to someembodiments, the at least a portion of the apparatus comprises aninternal passageway provided at least partially inside the apparatus.The present invention also provides a method of disinfecting arespiratory assistance apparatus and attachments for use with suchmethod of disinfecting the respiratory assistance apparatus.

A chamber is provided on or at the apparatus in which liquid can beheated to produce vapour or steam, the vapour being delivered to the atleast a portion of the apparatus (such as the internal passageway) todisinfect that portion with moist heat. The invention provides for thechamber being the same humidification chamber used to humidify the gasesflow prior to delivery to the patient during normal use of the apparatusto provide respiratory assistance. The invention also or alternativelyprovides for a separate chamber to be used. In this latter example, inthe disinfecting mode, the humidification chamber may be removed, andreplaced with a disinfecting chamber. The disinfecting chamber may be areusable, refillable chamber, or may be supplied pre-filled with therequired amount of disinfecting liquid and pre-sealed.

The invention provides for the use of water and therefore vapour orsteam to disinfect said at least a portion of the apparatus with moistheat. Other liquids, or combinations of liquids, could be used asrequired.

The invention provides for the source of liquid that is used fordisinfection to be a self contained part of the apparatus, namelylocated on or at the apparatus in use of the disinfection mode.

Referring to the Figures, a respiratory assistance apparatus 4 comprisesa housing 10 which may be generally cuboidal and may be arranged to beplaced on a table or tray, or mounted on a wall or some other support,as required or preferred.

A supply gases inlet 9 is provided, for example on the rear of thehousing, and is in fluid communication with a gases source such as ablower, fan or compressor (not shown), preferably mounted in the housing10 for delivering a gases flow. There may be ductwork within the housingwhich connects the gases source with the supply gases inlet 9, and thatductwork may be of a length and path direction selected as required.

The housing 10 is further provided with a supply gases outlet 11, whichmay project from the front of the housing 10, from which the gases flowexits.

Preferably, adjacent the supply gases outlet 11 is a patient inlet 13which may also project from the front of the housing 10, which leads toa patient outlet 8 which may project from the top of the housing 10. Thepatient inlet 13 and the patient outlet 8 are connected by anintermediate passageway, which in this example comprises an elbow 12that is bent along its length through 90°. The patient inlet 13 andpatient outlet 8 may be otherwise positioned depending on the apparatusconfiguration, with the elbow 12 configured to provide fluidcommunication between the patient inlet 13 and the patient outlet 8.Thus, the elbow 12 may be of some alternative configuration, includingbut not limited to straight, curved, or bent in more than one location.

In this example, a humidifier is provided having a chamber 5 comprisinga chamber inlet port 26 and a chamber outlet port 15. The ports 26, 15are provided on the rear of the chamber 5, and sealingly engage with thesupply gases outlet 11 and the patient inlet 13, respectively, such thatin use the gases flow enters the chamber 5 from the supply gases outlet11 through the chamber inlet port 26 and exits the chamber 5 to thepatient inlet 13 through the chamber outlet port 15.

The chamber 5 may be removably mounted on the housing 10, and in oneexample, may be slidably mounted on the front of the housing 10 bysliding the chamber 5 towards the rear of the housing 10 until the ports11, 26 and the ports 13, 15 engage. In another example, the chamber 5may be permanently mounted on the housing 10.

A heater 6 is provided which in this example comprises a heater plate 25on the housing 10, below the chamber 5. Other forms of heater areenvisaged and these may include a heater element built into the chamber5 itself or a non-contact heater such as an induction heater forexample.

A controller may be provided in the housing 10 which is arranged tocontrol the gases source and the heater. It will be appreciated that byproviding appropriate communication means, control may be effected, atleast in part, remote from the apparatus.

The apparatus 4 is operative according to at least two modes: arespiratory mode and a disinfection mode.

In the respiratory mode, the gases source is controlled to provide agases flow to the chamber 5. The gases flow passes into the chamberinlet port 26, across the chamber 5, and out of the chamber outlet port15. The heater 25 is controlled to heat liquid in the chamber 5 suchthat the incoming gases flow passes over the liquid and is humidified byvapour generated from the heated liquid. This heated and humidifiedgases flow exits the chamber 5 via the chamber outlet port 15 and isdelivered to a patient 1 via the elbow 12 and the patient outlet 8.While various interfaces are known and may be selected based onoperational parameters and user preferences, FIG. 1 shows a particularinspiratory tube 3 having a heating element 7 running therethrough, andcoupled at one end to the patient outlet 8 and at the other to a patientinterface 2 (shown as a nasal cannula).

In the disinfection mode, the gases source may be switched off, or maybe controlled to continue delivering a gases flow into the chamber 5 atthe same or a different flow rate. The heater is controlled to heatliquid in the chamber 5 to produce steam or vapour at or above a targetdewpoint temperature. The vapour fills the chamber 5 and is deliveredinto the elbow 12 and through the patient outlet 8. The vapour in theelbow 12 provides the moist heat that serves to disinfect the elbow 12and the patient outlet 8. The disinfection mode is operative for apredetermined duration in which the heater 25 is controlled such thatvapour continues to be generated and supplied to the elbow 12 throughoutthe duration of the disinfection mode.

The target dewpoint temperature is set sufficiently high that the vapourprovides the moist heat necessary to disinfect the elbow 12, at leastover the duration of the disinfection mode. The target dewpointtemperature is inversely proportional to the duration of thedisinfection mode, at least within a preferred temperature range of 70°C. to 100° C. Thus, a fixed target dewpoint temperature and disinfectionmode duration may be predetermined, or may be variable according to auser selection of one of the target dewpoint temperature or thedisinfection mode duration. A lookup table may be provided which relatesthe duration required for a range of target dewpoint temperatures. As anexample only, a range of dewpoint temperatures between 70° C. and 90° C.may achieve sufficient disinfection efficacy over a disinfection modeduration of between 15 and 45 minutes, preferably around 30 minutes. Aswill be appreciated, to ensure sufficient disinfection efficacy, asafety margin may be applied to the dewpoint temperature and/orduration.

In this example, the disinfection mode therefore requires no externalcomponents, or modifications to the apparatus 4, instead using thecomponents of the humidifier in a different manner to achievedisinfection. No external disinfection hoses or the like are required,and it is not required to remove the chamber 5 from the housing 10.

Optionally, an end cap 30 is provided which is arranged to be mounted onthe end of the elbow 12 at the patient outlet 8.

The cap 30 comprises an engaging formation 31 arranged to engage withthe end of the elbow 12 at the patient outlet 8 to mount the cap 30. Thecap 30 may further comprise a flow restrictor 32 arranged to restrictflow through the elbow 12 when the cap 30 is so mounted, to provide backpressure in the elbow 12 during the disinfection mode. The cap 30 mayfurther comprise an antibacterial filter. The cap 30 may also comprisean identifier such as a RFID tag, or a resistor which is used by theapparatus 4 to determine if the cap 30 is mounted on the elbow 12.

The apparatus 4 may comprise a chamber sensor operative to generate asignal indicative of whether the chamber 5 is mounted on the apparatus4. The chamber sensor may be operative to generate a signal indicativeof whether a specific chamber or type of chamber is mounted on theapparatus 4. The chamber sensor may comprise the combination of apressure/flow sensor and a flow restriction on the specific chamber, theflow restriction restricting gases flow through the chamber which can bedetected by the pressure/flow sensor.

The apparatus 4 may comprise a patient interface sensor operative togenerate a signal indicative of whether a patient interface is connectedto the apparatus 4, and to activate the disinfection mode only when thesignal is indicative that a patient interface is not connected to theapparatus 4. The patient interface sensor may be operative to detect thepresence of the cap 30 on the end of the elbow 12 at the patient outlet8, and to generate the signal indicative that a patient interface isconnected to the apparatus 4, when no cap 30 is detected.

The apparatus 4 may comprise a disinfection mode sensor operative togenerate a signal indicative that the apparatus 4 is to operateaccording to the disinfection mode. The disinfection mode sensor may beoperative to generate the signal by detecting at least one of: the cap30 being mounted on the end of the elbow 12 at the patient outlet 8; thechamber 15 being mounted on the housing 10; and/or a user input.

The apparatus 4 may comprise a chamber liquid level detector operativeto generate a signal indicative of a liquid level in the chamber 5. Theapparatus 4 may be operative, in dependence upon the liquid level signaldetected, to vary at least one of: the flow rate of the gases flow; thetarget dewpoint temperature of the vapour; and/or the duration of thedisinfection mode.

The liquid level detector may indicate when the disinfection liquid hasbeen entirely used, so as to determine whether a sufficient duration anddewpoint temperature combination has been achieved to provide thedesired disinfection efficacy.

The apparatus 4 may provide a drying mode, initiated subsequent to thedisinfection mode, wherein the elbow 12 and/or other components of thegases flow path are dried. This may be achieved using heat generated bythe heater when all of the liquid in the chamber 5 has been entirelyused, or via a separate heater element, or via increasing the gases flowrate through the elbow 12, for example. The duration of the drying modemay be predetermined, user controlled, or controlled in dependence onmoisture levels detected in the elbow 12.

A drying mode may also be provided to dry the moisture from componentsof the gases flow path, such as by operating the blower for a sufficientperiod after the liquid has been completely used, or after the heaterplate has been switched off and the remaining liquid cools and itsevaporation approaches an equilibrium state.

In another example, another method of disinfecting the elbow 12 isprovided. This example uses a separate disinfection chamber 35 which ismounted on the housing 10 for the duration of the disinfection mode.This method can therefore be used on an apparatus not provided with ahumidification chamber 5, or otherwise requires removal of thehumidification chamber 5 when provided.

In this example, the disinfection chamber 35 is mounted on the housing10 with the chamber inlet port 37 sealingly connected to the supplygases outlet 11 on the housing 10. A disinfection hose 41 is connectedbetween the chamber outlet port 39 and the end of the elbow 12 at thepatient outlet 8. End cap 30 is mounted on the end of the elbow 12 atthe patient inlet 13.

During the disinfection mode, the heater heats liquid in thedisinfection chamber 35 to produce vapour at or above a target dewpointtemperature. The vapour flows from the disinfection chamber 35, alongthe disinfection hose 41 and into the end of the elbow 12 at the patientoutlet 8. The vapour flows along the elbow 12, disinfecting the elbow12, and exits via the end cap 30 on the end of the elbow 12 at thepatient inlet 13.

The disinfection chamber 35 may be supplied pre-charged with a suitablevolume of disinfecting liquid, or may be provided with an injector inletor the like through which a suitable volume of disinfecting liquid maybe introduced into the chamber 35.

Referring additionally to FIGS. 8 to 15, a safety cap 41 is provided formounting on the end of the elbow 12 at the patient outlet 8 of theapparatus 4 during a disinfection mode. The safety cap 41 is used duringa disinfection mode in which the humidifier chamber 5, or thedisinfection chamber 35, is mounted on the apparatus 4 to generatevapour that passes through the apparatus 4, through the elbow 12, andexits the apparatus 4 via the patient outlet 8. It will be appreciatedthat without safety measures, vapour exiting the patient outlet 8 couldscald a user or other person near the apparatus 4. Similarly, portionsof the apparatus 4 impinged by the vapour could become dangerously warm.Broadly speaking, the safety cap 41 provides a means of mitigating theserisks by dispersing the vapour, so that it is not concentrated in asmall area, and by condensing the vapour.

The safety cap 41 comprises a connector 43 arranged to connect thesafety cap 41 with the patient outlet 8 at one end of the elbow 12 and aduct 44 extending through the connector 43 to form a gases flow pathwith the patient outlet 8. The vapour duct 44 is provided, at a positiondistal from the connector 43, with at least one vapour outlet 45 throughwhich vapour exits the duct 44 in a generally radially outward directionbut is retained within the safety cap 41. A concave inner roof 47provides a condensing surface positioned above the end of the duct 44and above the vapour outlet 45 such that vapour from the vapour outlet45 rises and contacts the roof 47. The vapour condenses on the roof 47,and the condensate drops from the roof 47 and is collected in acondensate reservoir 49 below.

The risk of vapour directly contacting a user adjacent the apparatus 1is therefore reduced by virtue of the tortuous path defined by thesafety cap 41, and at least a portion of the vapour is safely condensedand collected within condensate reservoir 49 for later disposal.

The safety cap 41 is arranged to provide a vapour flow path thatdissipates the heat from the vapour and/or prevents emission of ahazardous stream of vapour, at least during normal operating conditions.In particular, the vapour duct 44 initially directs the vapour upwardlyaway from the patient outlet 8, along a central axis of the safety cap41. The end of the duct 44 is closed by domed end wall 61 (as describedfurther below) such that vapour then flows generally radially outwardlythrough vapour outlet(s) 45, and subsequently upwardly into contact withroof 47.

The vapour duct 44 and vapour outlet 45 prevent vapour from flowing upthe duct 44 directly into contact with the roof 47 and creating a hotspot on the roof 47. Directing the vapour radially away from the vapourduct 44 also prevents any condensate from undesirably flowing back downthe duct 44 and into the patient outlet 8.

The roof 47 forms a condensing surface which is impacted by the vapourand which has a surface area that is considerably greater than thecross-sectional area of the duct 44, so that heat energy of the vapouris not concentrated on a particular area of the roof 47. The roof 47,together with other components forming the safety cap 41, serves todissipate heat from the condensing vapour.

In the illustrated example, the safety cap 41 is of multi-piececonstruction broadly comprising a base piece forming a lower part 44A ofduct 44 and connector 43, the condensate reservoir 49 mounted on thebase piece around connector 43, and a cap piece comprising an upper part44B of duct 44 and roof 47. These pieces may be arranged to be connectedtogether in any suitable manner, including using push fit or snap fittype connections. One or more pieces may alternatively be constructed asa single component.

Connector 43 is a tubular connector comprising a duct connector 51 andan optional electrical connector 53. Connector 43 may be of the same orsimilar structure to a gases tube connector of the type used to connecta gases tube to the apparatus 1 in normal use, i.e., between theapparatus 1 and a patient interface. When pushed onto the apparatus 1,the duct connector 51 receives part of the patient outlet 8 of theapparatus 1 to form a vapour flow path, whilst the electrical connector53, when provided, forms an electrical connection with the apparatus 1.Resilient clips 54 releasably engage with corresponding formations onthe apparatus 1 to secure the connector 43 onto the apparatus 1. Clips54 can be pressed inwardly to release the connector 43 from theapparatus 1.

The electrical connector 53 includes any power and/or sensor connectionsas are required between the safety cap 41 and the apparatus 1. Theelectrical connector 53 may include an identifier to enable theapparatus 1 to recognize that the safety cap 41 is connected to theapparatus 1. Once the safety cap 41 is recognized, the apparatus 1 mayautomatically begin a disinfection mode for example. The apparatus 1 maybe arranged to prevent activation of a disinfection mode until thesafety cap 41 has been connected and recognized by the apparatus 1. Inone example, the electrical connector 53 may include an identificationresistor which is used to detect the presence of the safety cap 41 onthe apparatus 1.

Condensate reservoir 49 comprises a substantially annular catch trayextending around connector 43. The catch tray 49 is generally circularor elliptical when viewed from above, and is of larger diameter thanroof 47 to minimize spillage of condensate dropping from the roof 47.The catch tray 49 further preferably comprises a spout 55 from whichcondensate can be poured to empty the tray 49 after vapour disinfection.The catch tray 49 may also be used to measure a predetermined volume offluid prior to commencement of a disinfection mode. The catch tray 49may comprise measuring indicia for this purpose, and/or the volume ofthe catch tray 49 may correspond to the volume of fluid required. Thusthe fluid may be measured in the catch tray 49 and then poured into thehumidifier chamber 5, or the disinfection chamber 35, using the spout55. The periphery of the catch tray 49 may comprise one or more tabs orother gripping formations 57 to facilitate gripping of the tray 49 by auser.

The upper cap piece comprises upper duct part 44B which is mounted on,and fluidly connected to, lower duct part 44A. Upper duct part 44B isclosed off by domed end wall 61. Below the domed end wall 61 are aplurality of vapour outlets 45 which in this example compriseequi-spaced slits formed in the duct wall. Any number and/or size and/orshape of vapour outlets 45 can be provided as required. The roof 47 isjoined to the upper duct part 44B by a plurality of radially outwardlyextending spokes 63, a vapour outlet 45 being provided between each pairof spokes 63. Spokes 63 add thermal mass and heat transfer conduits tothe safety cap 41 to assist in cooling the vapour by absorbing heattherefrom. The size and/or number of the spokes 63 may be selectedaccordingly. The periphery of the concave roof 47 leads to a downwardlydirected skirt 65 which assists in directing condensate down into thecatch tray 49, minimizing spillage. Skirt 65 also prevents or reducesthe amount of vapour ejected via the vapour outlets 45 that escapes thecap 41 and is able to contact a user, maintaining safe operation, atleast during normal operating conditions.

With reference to FIGS. 11 and 15 in particular, roof 47 may betransparent or opaque.

Safety cap 41 may optionally further comprise one or more fins or otherformations on the exterior of at least part of the cap 41, to prevent auser directly contacting the cap surface and/or to increase heatdissipation from the cap surface, for example roof 47. The inside of theroof 47 may comprise a hydroscopic structure to promote formation ofcondensation. The roof 47 and/or skirt 65 could comprise microstructuresto channel condensate droplet movement down to catch tray 49 as quicklyand/or directly as possible.

While the Figures show a particular embodiment of a safety cap accordingto the invention, various modifications or alternatives are includedwithin the scope of the invention. For example, other structures thatserve to disperse the vapour to prevent localized hot spots are alsoincluded within the scope of the invention, as are other structures thatpromote condensation.

With reference to FIGS. 16 to 21, apparatus 1 is arranged to operateaccording to a disinfection mode. This mode may be activatedautomatically, for example, when safety cap 41 is mounted on theapparatus 1, or activated when selected by a user. The disinfection modemay be prevented from activating until the apparatus 1 detects thesafety cap 41, the cap 30, or some other attachment used in thedisinfection mode.

Referring to FIG. 16, the disinfection mode is controlled via adisinfection controller 71 which receives information from sensors andinteracts with a gas flow control system 73 and a gas temperaturecontrol system 75. More particularly, flow control system 73 may beoperable to control a pressure and/or flow of gas along a gas flow paththrough the apparatus, at least when in the disinfection mode. It willbe appreciated that the same or separate circuitry may be used tocontrol flow when in a respiratory mode. Conversely, the temperaturecontrol system 75 may control heating of liquid used in disinfectionmode, such as via a heater plate provided in thermal communication witha chamber holding said liquid. According to some embodiments, heatingmay be provided along the gas flow path to maintain a desired dewpointtemperature and prevent condensation forming. Such heating may comprisea resistance wire heating element provided in a wall defining the gasflow path. Again the same or different circuitry may be employed tosimilar effect when in a respiratory mode.

With particular reference to FIGS. 17 and 21, the disinfectioncontroller 71 may be initiated by detecting when the safety cap 41 isconnected to the apparatus 1 using an identifier on the safety cap 41.In one example, this detection may be via a measurement of theelectrical resistance of a resistor in the electrical connector 53 ofcap 41. The detected resistance of the resistor is compared by thedisinfection controller 71 to a predetermined resistance valueassociated with the safety cap 41. For example if the detectedresistance exceeds the predetermined resistance value, this signals tothe disinfection controller 71 that the safety cap 41 is connected tothe apparatus 1. The disinfection controller 71 may then automaticallyinitiate a disinfection mode. The disinfection controller 71 mayalternatively use the resistance comparison to allow or prevent anoperator from initiating a disinfection mode. As will be appreciated,other forms of detection may be used. For example, apparatus 1 may beoperable to detect the presence of an RFID tag form part of the safetycap 41. Optical identification means may alternatively be provided.Alternatively, the detection may be omitted with the disinfection modebeing initiated by user input. Such control may additionally oralternatively be used for other embodiments of the invention that do notinclude the safety cap 41. For example, it may be used to detect thepresence of cap 30 or some other attachment used in the disinfectionmode.

Flow control system 73 controls the motor speed of the blower, fan orcompressor of apparatus 1, at least when in a disinfection mode. Theflow control system 73 processes gas flow signals from flow sensorswhich may be positioned at one or more points along the gas flow path.Additionally or alternatively, flow may be determined based on a signalfrom a blower motor speed sensor. The apparatus 1 may comprise lookuptables that translate a given motor speed into a flow for determinedapparatus configurations (e.g. whether cap 30 or safety cap 41 isconnected).

Chamber detection system 74 may be configured to process the outputsfrom the gas flow sensor and the blower motor speed sensor to determinewhether or not the humidifier chamber 5, or the disinfection chamber 35,or safety cap 41, or cap 30, or some other attachment is connected tothe apparatus, and whether to initiate the disinfection modeaccordingly. Known flow profiles of components may be stored in a memoryof the apparatus 1 and used to determine which components are connectedbased on a comparison with detected flow.

Gas temperature control system 75 controls the heat produced by theheater plate of the humidifier of apparatus 1 using a signal from a gastemperature sensor at or near the patient outlet 8, and/or a signal froma heater temperature sensor at or near the chamber. The gas temperaturesensor may be provided in or at the elbow 12, or elsewhere disinfectionis required.

Liquid out detection system 76 may be configured to detect when there isno more liquid in humidifier chamber 5 using signals from the ambienttemperature sensor and the heater plate temperature sensor.

With reference to FIGS. 18 to 20, a preferred embodiment of an algorithm181 used by the controller 71 is described that uses the systems 73, 74,75 and 76, and sensors described above.

The algorithm 180 may begin at step 181 with checks that the apparatusis properly configured for performing the disinfection cycle. Forexample, controller 71 may detect whether safety cap 41 (or otherdisinfection mode equipment) and chamber 5 are fitted to apparatus 1.There may also be a check that there is liquid in the chamber 5. Thelatter may comprise not just detecting a presence or absence of a liquidbut a level thereof. While any form of liquid level detector may beused, liquid level may be determined based on the amount of energy usedto generate a given change in temperature. For example, current or powersupplied to the heater plate may be monitored and a water level inferredbased on whether a particular temperature increase is achieved within apredetermined time range. Too rapid a rise in temperature may indicatetoo little liquid in the chamber. Conversely, a less than expected risein temperature within a given time period may indicate that too muchliquid has been provided. As discussed elsewhere, it is preferable thatthe disinfection cycle terminates with a drying cycle and too muchliquid may prevent this or undesirably lengthen the cycle.

At step 181, the heater plate is controlled to heat the liquid andgenerate vapour which flows from the chamber, through the elbow 12 andinto duct 44 of safety cap 41, via patient outlet 8. Steps 181 and 182may be combined to some extent where liquid level is determined based onthe heater plate duty cycle. Vapour is maintained in the elbow 12 at atemperature above a minimum threshold, such as 70° C. for example, for atime period necessary for a sufficient level of disinfection. Duringwarm up of the apparatus 1 and the disinfection part 183 of the cycle,preferably, flow controller 73 may deactivate the compressor used toenhance flow of gas through the apparatus, with flow being generated dueto expansion resulting from vaporization. Alternatively, the flowcontroller 73 may control the compressor to only generate a relativelysmall increase in flow. Equipment used for respiratory assistance isconfigured to generate relatively low temperature humidified gases flowsthat are suitable for receiving in a patient airway. Higher temperaturesare required for disinfection. Reducing or inhibiting flow enhancementprovided by the compressor can enable vapour to be generated with therequired dewpoint temperature using substantially the same apparatus asthat used for providing respiratory assistance and without requiringadditional heating. For some compressors used for providing respiratoryassistance, low levels of flow may be generated by applying power to amotor of the compressor in pulses, with “ON” pulses in which power issupplied thereto being interspersed by “OFF” cycles when no power issupplied to the motor. Braking may additionally or alternatively beprovided.

Completion of the disinfection part 183 of the cycle may be determinedbased on stored cycle times for a given apparatus configuration and apredetermined or detected level of liquid present in the chamber 5 atthe start of the process. Once detected, a cool down and drying phase184 is initiated that ensures that the walls defining the gas pathwayare dry and that they are cooled to a sufficient degree to becomfortably handled by a user and/or used to provide respiratoryassistance. This phase 184 preferably comprises increasing the flowenhancement provided by the compressor to dry moisture from theapparatus and then to draw relatively cooler air through the apparatusto cool it. However, rapidly increasing the flow may generate a strongjet of heated humidified gas which may be hazardous. For example, evenwhere safety cap 71 is used, a rapid increase in flow rate may result ina heated vapour stream or cloud forming about the safety cap 71 unlessthe safety cap 71 is designed to cope with such high flow rates. Thus,according to preferred embodiments, the flow controller 73 graduallyramps up or increases flow to gradually clear the apparatus 1 of highenergy vapour.

At step 185, an absence of liquid in chamber 5 is detected and thedisinfection mode is terminated provided that the temperature of wallsforming the gas pathway have been sufficiently cooled. For example, atemperature at the elbow 12 may be required to have fallen below apredetermined threshold. The heater plate and the compressor are turnedoff. A signal may be generated to indicate to the operator that thedisinfection mode has finished.

The apparatus 1 may be arranged to log one or more parameters of thedisinfection process, including but not limited to successful completionof a disinfection cycle, unsuccessful completion of a disinfectioncycle, if unsuccessful the reason therefor, a length and/or temperatureand/or temperature profile used in the cycle. Such data may be displayedon the apparatus 1 or communicated to remote processing equipment usedto collate, analyze or present the data. Thus apparatus 1 may be adaptedfor wired and/or wireless communication of the data.

From the foregoing it will be seen that apparatus and methods areprovided which allow reliable, effective disinfection of an intermediatepassageway of a respiratory assistance apparatus, which do not requireremoval of the intermediate passageway, or any manual intervention ormanual cleaning of the passageway. Additionally, apparatus and methodsare provided in which disinfecting vapour is generated in situ on theapparatus. Examples are also provided in which the components of thehumidifier which are already present on the apparatus, are used in adisinfection mode.

Unless the context clearly requires otherwise, throughout thedescription, the words “comprise”, “comprising”, and the like, are to beconstrued in an inclusive sense as opposed to an exclusive or exhaustivesense, that is to say, in the sense of “including, but not limited to”.

Although this invention has been described by way of example and withreference to possible embodiments thereof, it is to be understood thatmodifications or improvements may be made thereto without departing fromthe scope of the invention. The invention may also be said broadly toconsist in the components, elements and features referred to orindicated in the specification of the application, individually orcollectively, in any or all combinations of two or more of saidcomponents, elements or features. Furthermore, where reference has beenmade to specific components or integers of the invention having knownequivalents, then such equivalents are herein incorporated as ifindividually set forth.

Any discussion of the prior art throughout the specification should inno way be considered as an admission that such prior art is widely knownor forms part of common general knowledge in the field.

What is claimed is:
 1. A respiratory assistance apparatus adapted todeliver a gases flow to a user or patient, the apparatus comprising: ahousing provided with or configured to receive a chamber and a heater,the chamber comprising at least one chamber port connected to, orarranged to be connected to, at least one intermediate passageway,wherein the apparatus is operative according to a disinfection mode ofpredetermined profile in which the heater heats a liquid in the chamberto produce vapour or steam at or above a target dewpoint temperature,and wherein the apparatus is arranged such that vapour is delivered tothe intermediate passageway to disinfect the intermediate passagewaywith moist heat, the vapour being at or above the target dewpointtemperature and continuing to be delivered to the intermediatepassageway throughout the predetermined duration of the disinfectionmode.
 2. The apparatus of claim 1, wherein the at least one chamber portcomprises a chamber inlet port and a chamber outlet port, the chamberinlet port being arranged to be in fluid communication in use with agases source in the housing.
 3. The apparatus of claim 1 or claim 2,wherein the chamber comprises part of a humidifier of the apparatus, thehumidifier being arranged to humidify the gases flow prior to deliveryof the gases flow to the user or patient when the apparatus is operatingin a non-disinfection mode.
 4. The apparatus of any one of the precedingclaims, wherein the chamber comprises a disinfection chamber.
 5. Theapparatus of any one of the preceding claims, wherein the chamber isremovably mountable on or connectable to the apparatus.
 6. The apparatusof any one of the preceding claims, wherein the chamber comprises anidentifier, the apparatus being operative to detect the identifier andthus the presence of the chamber.
 7. The apparatus of any one of thepreceding claims, wherein the intermediate passageway comprises aninternal passageway located at least partially within the housing. 8.The apparatus of any one of the preceding claims, wherein theintermediate passageway comprises a conduit.
 9. The apparatus of any oneof the preceding claims, wherein the intermediate passageway directly orindirectly connects a gases inlet that allows a gases flow into thehousing with a patient outlet that delivers gases to the user orpatient.
 10. The apparatus of any one of the preceding claims, wherein,during the disinfection mode, a first end of the intermediate passagewayis connectable to an outlet of the chamber.
 11. The apparatus of claim10, wherein the first end of the intermediate passageway is connectableto the chamber outlet port via a removable disinfection tube whichdelivers vapour or steam to the intermediate passageway.
 12. Theapparatus of claim 11, wherein the disinfection tube comprises heatermeans.
 13. The apparatus of any one of the preceding claims, wherein theintermediate passageway comprises an elbow having opposed ends linked byan intermediate bent portion.
 14. The apparatus of any one of thepreceding claims, wherein the apparatus comprises or is communicativelycoupled to at least one sensor operative to generate a signal indicativeof any one or more of flow rate, moisture content or temperature. 15.The apparatus of claim 16, wherein at least one said sensor is adapted,in use, to measure a parameter of the gases flow in or proximate to theintermediate passageway.
 16. The apparatus of any one of the precedingclaims, comprising a cap having an engaging formation arranged to engagewith and/or fluidly couple to one end of the intermediate passageway.17. The apparatus of claim 18, wherein the cap comprises a flowrestrictor arranged to restrict flow of fluid through the intermediatepassageway when the cap is so mounted to provide a back pressure in theintermediate passageway during the disinfection mode.
 18. The apparatusof claim 18 or claim 19, wherein the cap comprises a filter.
 19. Theapparatus of any one of claims 18 to 20, wherein the cap comprises anidentifier.
 20. The apparatus of any one of the preceding claims,wherein the apparatus is operative to heat the liquid to produce vapouror steam at or above a target dewpoint temperature.
 21. The apparatus ofany one of the preceding claims, wherein the apparatus is operative toheat the liquid to produce vapour or steam at or above a target dewpointtemperature selected by a clinician or user.
 22. The apparatus of claim21, wherein the target dewpoint temperature is variable by a user and/orin accordance with a predetermined program.
 23. The apparatus of any oneof the preceding claims, wherein the target dewpoint temperature isgreater than 70° C., or greater than 80° C., or greater than 90° C. 24.The apparatus of any one of the preceding claims, wherein the targetdewpoint temperature is less than 110° C., or less than 105° C., lessthan 95° C.
 25. The apparatus of any one of the preceding claims,wherein the predetermined duration is between 15 minutes and 45 minutes.26. The apparatus of claim 25, wherein the predetermined duration isapproximately 30 minutes.
 27. The apparatus of any one of the precedingclaims, wherein the predetermined duration is less than 60 minutes orless than 50 minutes
 28. The apparatus of any one of the precedingclaims, wherein the apparatus is operative to control the duration ofthe disinfection mode in dependence, at least in part, upon the targetand/or a measured dewpoint temperature.
 29. The apparatus of any one ofthe preceding claims, wherein the apparatus is operative to control theduration of the disinfection mode by reference to a lookup tablerelating the duration of the disinfection mode to a range of targetand/or measured dewpoint temperatures, or to control the target and/ormeasured dewpoint temperature by reference to at least one of a lookuptable, an algorithm and a formula relating the target and/or measureddewpoint temperature to a duration of the disinfection mode.
 30. Theapparatus of any one of the preceding claims, comprising a chambersensor operative to generate a signal indicative of whether the chamberis mounted on the apparatus.
 31. The apparatus of any one of thepreceding claims, comprising a patient interface sensor operative togenerate a signal indicative of whether a patient interface is connectedto the apparatus.
 32. The apparatus of claim 30 or 31, wherein theapparatus is configured to activate the disinfection mode only when thesignal indicates that a patient interface is not connected to theapparatus.
 33. The apparatus of any one of the preceding claims,comprising a disinfection mode sensor operative to generate adisinfection mode activation signal.
 34. The apparatus of claim 33,wherein the disinfection mode sensor is operative to generate thedisinfection mode activation signal by detecting at least one of a capor other disinfection mode attachment being mounted on one end of theintermediate passageway; the chamber being mounted on the housing; and auser input.
 35. The apparatus of any one of the preceding claims,comprising a chamber liquid level detector.
 36. The apparatus of any oneof the preceding claims, operative in a drying mode subsequent to thedisinfection mode, wherein the intermediate passageway and/or componentsare dried.
 37. A cap for use with the respiratory assistance apparatusof any one of the preceding claims, the cap comprising an engagingportion arranged to engage with and/or fluidly couple to one end of theintermediate passageway to mount the cap on said end, the cap comprisingat least one of: a flow restrictor arranged to restrict flow of liquidthrough the intermediate passageway when the cap is so mounted toprovide back pressure in the intermediate passageway during thedisinfection mode, a filter.
 38. The cap of claim 37, wherein the filteris an anti-bacterial filter.
 39. The cap of claim 37 or claim 38,wherein the flow restrictor comprises an orifice.
 40. The cap of any oneof claims 37 to 39, comprising a temperature sensor operative togenerate a signal indicative of the temperature of the gases flow at orproximate to the cap.
 41. The cap of any one of claims 37 to 40,comprising an identifier.
 42. The cap of any one of claims 37 to 41,comprising an open-ended cavity which defines a volume suitable formeasuring an amount of a liquid for use in the apparatus in thedisinfection mode.
 43. A method of disinfecting at least a part of arespiratory assistance apparatus, the respiratory assistance apparatusbeing adapted to deliver gases flow to a user or patient, the methodcomprising subjecting said at least a part of the respiratory assistanceapparatus to a humidified gases flow at or above a target dewpointtemperature for a predetermined duration of time of a disinfection mode.44. The method of claim 43, wherein the apparatus comprises a chamberprovided with a port in fluid communication with an intermediatepassageway, the method comprising steps of: heating a liquid in thechamber to produce vapour or steam at or above a target dewpointtemperature; delivering the vapour through the port to the intermediatepassageway; and continuing to deliver vapour at or above the targetdewpoint temperature through the port to the intermediate passagewaythroughout the predetermined duration of the disinfection mode.
 45. Themethod of claim 43 or claim 44, wherein the target dewpoint temperatureis predetermined or selected by a user or determined based on otherdetected parameters.
 46. The method of claim 44 or 45, comprisingdetecting the presence or absence of any one or more of the chamber, anattachment for use with the apparatus in the disinfection mode, andliquid in the chamber, and/or a predetermined level of liquid in thechamber, wherein the disinfection mode is automatically activated or isable to be activated following a positive detection of said chamberand/or attachment and/or liquid, and/or the predetermined level ofliquid.
 47. The method of any one of claims 43 to 46 wherein theapparatus comprises a compressor for controlling a flow rate of thehumidified gases flow, comprising controlling the compressor to provideno or only a low level of increased flow during a main disinfectionphase of the disinfection mode.
 48. The method of claim 47, wherein thelow level of flow is less than about 10 L/min or less than about 2 L/minor less than 1 L/min.
 49. The method of claim 47 or 48, comprising,prior to termination of the disinfection mode, controlling thecompressor to provide a ramped increase in flow to dry and/or cool atleast a portion of the apparatus.
 50. The method of claim 49, whereinthe compressor provides a ramped increase to greater than 20 L/min orgreater than 40 L/min or greater than 60 L/min.
 51. The method of anyone of claims 47 to 50 comprising switching off of the heater and/or thecompressor upon detection of any one or more of an absence of liquid inthe chamber, a temperature of a portion of the apparatus falling below apredetermined threshold, a temperature detected inside the apparatusfalling below a predetermined threshold and elapse of a predeterminedtime period.
 52. The method of any one of claims 43 to 51, comprisinggenerating and/or displaying a signal indicative of whether thedisinfection mode was completed successfully, and/or log one or moreparameters relating to the disinfection mode cycle.
 53. A respiratoryassistance apparatus adapted to deliver a gases flow to a user orpatient, comprising a housing having a patient outlet, a chamber, and anintermediate gases flow path between the patient outlet and the chamber,the apparatus being operative during a disinfection mode ofpredetermined profile, to heat the liquid to generate vapour or steam ator above a target dewpoint temperature and deliver the vapour from thechamber to the intermediate gases flow path to disinfect theintermediate gases flow path with moist heat throughout thepredetermined duration of the disinfection mode.
 54. A method ofdisinfecting at least part of a respiratory assistance apparatus adaptedto deliver gases flow to a user or patient according to a disinfectingmode comprising the steps of: connecting a chamber to the apparatus;heating liquid in the chamber to produce vapour or steam at or above atarget dewpoint temperature; and delivering the vapour portion of theliquid to a component of the apparatus to disinfect that component withmoist heat.
 55. The apparatus of any one of claim 1 to 36 or 53comprising a safety cap provided with a connector arranged to fluidlycouple the safety cap to a downstream end of the intermediatepassageway, and a duct forming a vapour flow path into the safety cap,the safety cap being adapted to disperse and/or condense vapour receivedthereby.
 56. The apparatus of claim 55, wherein the safety cap comprisesa condensing surface onto which vapour from the duct condenses.
 57. Theapparatus of claim 56 or 57 comprising a condensate reservoir adapted toreceive condensate generated by the safety cap.
 58. A respiratoryassistance apparatus adapted to deliver a gases flow to a user orpatient, the apparatus comprising a housing provided with or configuredto receive a chamber and a heater, the chamber comprising at least oneport connected to, or arranged to be connected to, at least oneintermediate passageway, the apparatus being operative according to adisinfection mode to heat liquid in the chamber to generate vapour orsteam at or above a target dewpoint temperature and deliver the vapourfrom the chamber to the intermediate passageway to disinfect theintermediate passageway with moist heat, the apparatus furthercomprising a safety cap provided with a connector arranged to connectand/or fluidly couple the safety cap to a downstream end of theintermediate passageway, thereby defining a gases pathway from thechamber to the safety cap, the safety cap being adapted to, in use inthe disinfection mode, disperse and/or condense at least a portion ofvapour received thereby.
 59. The apparatus of claim 58, comprising aduct defining the gases pathway into the safety cap, the safety capfurther comprising a condensing surface onto which vapour from the ductcondenses.
 60. The apparatus of claim 58 or 59, comprising a condensatecollector adapted to collect at least a portion of the condensategenerated by the safety cap.
 61. A safety cap for use with therespiratory apparatus of any one of claim 1 to 36 or 53, the safety capcomprising a connector arranged to fluidly couple the safety cap to adownstream end of the intermediate passageway, and a duct forming avapour flow path into the safety cap, the safety cap being adapted to,in use in a disinfecting mode, disperse and/or condense vapour receivedthereby.
 62. The safety cap of claim 61 comprising a condensing surfaceonto which vapour from the duct condenses.
 63. The safety cap of claim62 wherein the condensing surface has a surface area greater than thecross sectional area of the duct.
 64. The safety cap of claim 62 orclaim 63 wherein the condensing surface comprises a domed ceiling intowhich the duct directs the vapour flow path.
 65. The safety cap of claim64 comprising a skirt extending generally downwards from a peripheraledge of the ceiling to define an area for holding vapour and/ordirecting flow of condensate.
 66. The safety cap of any one of claims 62to 65 adapted to direct vapour radially outwardly of the connector priorto the vapour impacting on the condensing surface.
 67. The safety cap ofany one of claims 61 to 66 wherein the duct is defined by a wall havingat least one vapour outlet through which vapour can flow away from alongitudinal axis of the duct.
 68. The safety cap of claim 67 whereinthe or each vapour outlet comprises a slit formed in the wall definingthe duct.
 69. The safety cap of any one of claims 62 to 66 or claim 67or 68 when dependent on any one of claims 62 to 66 wherein thecondensing surface is connected to the duct via at least one spokeextending between the condensing surface and the duct.
 70. The safetycap of claim 69 wherein a vapour outlet is provided in the wall of theduct between one or more adjacent pairs of said spokes.
 71. The safetycap of any one of claims 61 to 70, wherein the duct is terminated at anend distal from the intermediate passageway by an end wall.
 72. Thesafety cap of any one of claims 61 to 71 comprising an identifier. 73.The safety cap of claim 72 wherein the identifier comprises a resistor,the resistance of which is detected by the apparatus when the safety capis mounted on the apparatus.
 74. The safety cap of any one of claims 61to 73 comprising one or more surfaces having a hydroscopic structurearranged to promote the formation of condensate.
 75. The safety cap ofany one of claims 61 to 74 comprising microstructures arranged tochannel flow of condensate.
 76. The safety cap of any one of claims 61to 75 comprising a condensate collector that defines a reservoir intowhich condensed vapour is collected.
 77. The safety cap of claim 76wherein the condensate collector comprises a substantially annular catchtray extending around the periphery of the connector.
 78. The safety capof claim 76 or 77 wherein the condensate collector comprises a spout tofacilitate pouring of liquid from the condensate reservoir.
 79. Thesafety cap of any one of claims 76 to 78 wherein the condensatereservoir is arranged to measure a pre-determined volume of liquid foruse during the disinfecting mode of the respiratory apparatus.
 80. Arespiratory assistance apparatus adapted to deliver gas to a user orpatient, the apparatus comprising: a housing provided with or configuredto receive a chamber and a heater, the chamber comprising at least onegas port connected to, or arranged to be connected to, at least oneintermediate passageway, the apparatus being operative according to avapour disinfection mode to disinfect the at least one intermediatepassageway with moist heat, the apparatus comprising a controller forcontrolling operation of the apparatus in the disinfection mode, toactivate the heater to heat liquid in the chamber to generate vapour ator above a target dewpoint temperature for at least a portion of theduration of the disinfection mode.
 81. The apparatus of claim 80wherein, in an initialization phase, the controller is arranged todetect the presence or absence of any one or more of the chamber, anattachment for use with the apparatus in the disinfection mode, andliquid in the chamber, and/or a level of liquid in the chamber.
 82. Theapparatus of claim 80 or 81 comprising a compressor in fluidcommunication with the chamber for urging gases through the chamber tothe at least one intermediate passageway, wherein during a warm up phaseand/or a main disinfecting phase, the controller is adapted to controlthe heater to generate vapour and to control the compressor to provideno or only a low level of increased flow.
 83. The apparatus of any oneof claims 80 to 82 wherein, prior to termination of the disinfectionmode, the controller is configured to control the compressor to providea ramped increase in flow so as to dry and/or cool down the at least oneintermediate passageway.
 84. The apparatus of any one of claims 80 to83, wherein the controller is configured to switch of the heater and/orthe compressor upon detection of any one or more of an absence of liquidin the chamber, a temperature of a portion of the apparatus fallingbelow a predetermined threshold, a temperature detected inside theapparatus falling below a predetermined threshold and elapse of apredetermined time period.
 85. The apparatus of any one of claims 80 to84 wherein the controller is arranged to generate a signal indicative ofwhether the disinfection mode was completed successfully and/or log oneor more parameters relating to the disinfection mode.